terraingen

function round(x)
  	if x%2 ~= 0.5 then
    	return math.floor(x+0.5)
  	end
  	return x-0.5
end
function grid(n, grid)
	return math.floor(n/grid + 0.5)*grid
end
function putTexture(part, frontF, backF, topF, bottomF, leftF, rightF, className)
	local faces = {"Front", "Back", "Top", "Bottom", "Left", "Right"}
	for i,f in pairs(faces) do
		local decal = Instance.new(className)
		decal.StudsPerTileU = 2.6
		decal.StudsPerTileV = 2.6
		if i == 1 then decal.Texture = frontF decal.Name = f end
		if i == 2 then decal.Texture = backF or frontF decal.Name = f  end
		if i == 3 then decal.Texture = topF or frontF decal.Name = f  end
		if i == 4 then decal.Texture = bottomF or frontF decal.Name = f end
		if i == 5 then decal.Texture = leftF or frontF decal.Name = f  end
		if i == 6 then decal.Texture = rightF or frontF decal.Name = f  end
		decal.Face = f
		decal.Parent = part
	end
	return part
end
function QuickCreateInstance(className, properties)
	local inst = Instance.new(className)
	for propertyName,propertyValue in pairs(properties or {}) do
		inst[propertyName] = propertyValue
	end
	return inst
end

local collectionService = game:GetService("CollectionService")
local posToGen = Vector3.new(10000, 10000, 10000)
posToGen = Vector3.new(grid(posToGen.X, 2.6), grid(posToGen.Y, 2.6), grid(posToGen.Z, 2.6))

local x1 = 500
local y1 = 1
local z1 = 500

local seed = math.random()*100

local terrainBlocks = workspace:FindFirstChild("TerrainBlocks") or Instance.new("Model", workspace)
terrainBlocks.Name = "TerrainBlocks"

local oldBlockBehind = nil
for x = 1, z1 do
	local line = Instance.new("Model", terrainBlocks)
	line.Name = "Line " .. x
	for z = 1, x1 do
		for y = 1, y1 do
			local blockType = "grass"--math.noise(x/150, seed*16, z/150) > 0.4 and "stone" or "grass"

			local height = math.sqrt(13 + (math.noise(x/160, seed, z/160)*10 + math.noise(x/500, seed*5, z/500)*7))*3

			local pos = Vector3.new(x * 2.6, (round((height*26) / 2.6) * 2.6) - (y * 2.6), z * 2.6) + posToGen - Vector3.new(x1*2.6/2, 0, z1*2.6/2)

			local blockBehind = line:FindFirstChild("B " .. grid(pos.X, 2.6)/2.6 .. "," .. grid(pos.Y, 2.6)/2.6 .. "," .. grid(pos.Z - 2.6, 2.6)/2.6)
			if not blockBehind or (blockBehind and collectionService:HasTag(blockBehind, blockType) == false) then
				if oldBlockBehind then
					local oldLine = terrainBlocks:FindFirstChild("Line " .. x - 1)
					if oldLine then
						local sideBlock = oldLine:FindFirstChild("B " .. grid(oldBlockBehind.CFrame.p.X - 2.6, 2.6)/2.6 .. "," .. grid(oldBlockBehind.CFrame.p.Y, 2.6)/2.6 .. "," .. grid(oldBlockBehind.CFrame.p.Z + oldBlockBehind.Size.Z/2 - 0.5, 2.6)/2.6)
						if sideBlock and sideBlock.Size.Z == oldBlockBehind.Size.Z then
							sideBlock:Destroy()
							oldBlockBehind.Size = sideBlock.Size + Vector3.new(2.6, 0, 0)
							oldBlockBehind.CFrame = CFrame.new(sideBlock.CFrame.p.X + 1.3, oldBlockBehind.CFrame.p.Y, oldBlockBehind.CFrame.p.Z)
							-- debug
							--for _,c in pairs(oldBlockBehind:GetChildren()) do
							--	if c:IsA("Texture") then c.Color3 = Color3.new(0, 0, 1) end
							--end
						end
					end
				end

				--local chunkPos = Vector3.new(grid(pos.X/2.6, 16), grid(pos.Y/2.6, 16), grid(pos.Z/2.6, 16))

				--local chunk = chunks:FindFirstChild(chunkPos.X .. "," .. chunkPos.Y .. "," .. chunkPos.Z) or Instance.new("Model", chunks)
				--chunk.Name = chunkPos.X .. "," .. chunkPos.Y .. "," .. chunkPos.Z

				local block = Instance.new("Part")
				block.Material = "Fabric"
				block.Anchored = true
				block.Size = Vector3.new(2.6, 2.6, 2.6)
				block.CFrame = CFrame.new(grid(pos.X, 2.6), grid(pos.Y, 2.6), grid(pos.Z, 2.6))
				block.Name = "B " .. grid(pos.X, 2.6)/2.6 .. "," .. grid(pos.Y, 2.6)/2.6 .. "," .. grid(pos.Z, 2.6)/2.6
				--if y == 1 then
				if blockType == "grass" then
--					if y == 1 then
						putTexture(block, "rbxassetid://3132023393", "rbxassetid://3132023393",
							"rbxassetid://3131912045", "rbxassetid://3103457697",
						 	"rbxassetid://3132023393", "rbxassetid://3132023393", "Texture")
--					elseif y >= 2 then
--						putTexture(block, "rbxassetid://3103457697", "rbxassetid://3103457697",
--							"rbxassetid://3103457697", "rbxassetid://3103457697",
--						 	"rbxassetid://3103457697", "rbxassetid://3103457697", "Texture")
--					end
				--elseif y == 2 then
				else
					putTexture(block, "rbxassetid://3131912893", "rbxassetid://3131912893",
						"rbxassetid://3131912893", "rbxassetid://3131912893",
					 	"rbxassetid://3131912893", "rbxassetid://3131912893", "Texture")
				end
	--			elseif y >= 3 then
	--				putTexture(block, "rbxassetid://75880927", "rbxassetid://75880927",
	--					"rbxassetid://75880927", "rbxassetid://75880927",
	--				 	"rbxassetid://75880927", "rbxassetid://75880927", "Texture")
				--end
				block.Parent = line
				collectionService:AddTag(block, blockType)
			else
				if blockBehind:IsA("ObjectValue") then blockBehind = blockBehind.Value end
				if collectionService:HasTag(blockBehind, blockType) then
					blockBehind.Size = blockBehind.Size + Vector3.new(0, 0, 2.6)
					blockBehind.CFrame = CFrame.new(blockBehind.CFrame.p + Vector3.new(0, 0, 2.6/2))
					blockBehind.Name = "B " .. grid(pos.X, 2.6)/2.6 .. "," .. grid(pos.Y, 2.6)/2.6 .. "," .. grid(pos.Z, 2.6)/2.6
					--QuickCreateInstance("ObjectValue", {Name = "B " .. grid(pos.X, 2.6)/2.6 .. "," .. grid(pos.Y, 2.6)/2.6 .. "," .. grid(pos.Z - 2.6, 2.6)/2.6, Value = blockBehind, Parent = blockBehind})
					oldBlockBehind = blockBehind
				end
			end
		end
	end
	wait()
end